1. Field of the Invention
The present invention relates to an automotive extrusion-molded product such as a trim, weather strip, and window molding that is used at a vehicle body opening such as an automotive door, trunk, and window, and a manufacturing method therefor.
2. Description of Related Art
Conventionally, as an extrusion-molded product of this type such as trim, weather strip, and window molding that is used at a vehicle body opening of an automobile, a metallic core material formed with fishbone-shaped cut portions has been used. The conventional automotive extrusion-molded product is manufactured by a process described as follows. First, the fishbone-shaped cut portions are punched out from the metallic core material having a cross-sectional shape of a flat plate, and then by extrusion-molding synthetic resin, rubber, or the like, a coating layer and holding members are formed on the flat-plate metallic core material having the cut portions. Subsequently, the product is bent substantially into a U shape in the cross section.
As environmental problems have become serious in recent years, in order to make the metallic core material light in weight and able to be recycled, it is desired to change the material to hard synthetic resin. However, when the hard synthetic resin core material is produced with the flat plate in the same way as that for the metallic core material, it is very difficult to bend the material into a U shape in the cross section. Therefore, a synthetic resin core material is extrusion-molded into a U shape in advance, and the cut portions of difficult shapes are formed by a punching machine, by which a synthetic resin core material having cut portions is formed. Subsequently, by extrusion-molding, a coating body is attached on the outer periphery of the synthetic resin core material having a U shape in the cross section, and a plurality of opposed holding members for pressing, which are used to hold a flange of vehicle body opening of an automobile, are formed on the inside surface of the core material having the U-shaped cross-section.
However, in order to increase a holding force of the holding members with respect to a flange of a vehicle body opening of an automobile, it is necessary to surely decrease the spacing between the opposed holding members, which presents a serious problem in that it is difficult to extrusion-mold the holding members having a desired shape on the inner peripheral surface substantially having a U-shaped cross section because the spacing is narrow.